Hach 5B testing very slow

[ChrisBeall]

When i test softened water using the Hach 5B test, the results are almost immediate. When the pink granular material is mixed into the water sample, it dissolves quickly and the water is clear (pink, but completely transparent).

When I test hardened water, either from the incoming supply or when the softener is overdue to regenerate, the pink material does not dissolve for a long time and the water sample is cloudy. I also see occasional tiny black particles with tails of dissolving material. I tried heating the water sample for 3-4 seconds in a microwave to see if that would improve the dissolving rate, but it helped little, if at all.

I first noticed this in the results I was getting from the test. Today I took a sample (using water heated as above) swirled it for a minute or so, then started dropping in the liquid reagent. After 4 drops, I got a pink-to-blue color change. So I kept swirling the water and after 10-15 seconds the water gradually turned pink again. I added another drop and got blue. Swirled the solution again for 15 seconds and it gradually turned pink. I repeated this until I had added 10 drops, then stopped and ate lunch. After 20-30 minutes I resumed adding a drop at a time, getting a blue indication, then swirling until the solution again turned pink. Eventually I reached a total of 20 drops (consistent with the 20gpg hardness measured in previous tests) at which point no amount of swirling caused the blue color to revert to pink and the solution appeared clear, i.e. no cloudiness.

In all, this process took about an hour.

Now that I know how to get consistent results (much patience...) I can proceed with diagnosis of another issue, but I haven't seen anyone else mention this difficulty. Why might this happen?

 

[ditttohead]

How old is the Hach 5B test? They do have a limited shelf life but when stored correctly I would get a couple years out of them easily.

 

[Sponsor]

 

[Hachi]

I had the same experience as ChrisBeall. After 8 drops, the pink color started turning blueish-purple, then back to pink with swirling or a little time.
Each subsequent drop did the same, but the color became darker and more purple. At 16 drops, it looked blue, but slowly turned a very dark purple. One more drop and it became totally blue and did not change further. I suspect this is the endpoint, 17 grains for me, and not 8. I doubt age of the reagents has anything to do with it, but I could be wrong. I just purchased the kit. No answers from the forum on this behavior. I doubt my and ChrisBeall's experience are uncommon ones. The company is remiss in failing to give guidance on this.